the older brother, tamerlan tsarnaev, was 26. nbc news learned he spent six months last year outside of the country. authorities are still piecing together where he went and what he did during that time. there are many questions tonight. joining me to help answer them is nbc investigative correspondent michael isikoff and former director of the national counterterrorism center michael leiter. and former fbi profiler clint van zandt. let me start with michael leiter. the other day, it seems like a year ago, two, three days ago you, had this sense, professional instinct, if you will, that this killer, one of the two bombers, was a local. tell me how you came to that assessment. >> well, chris, my take -- >> he is a local. >> he is a local and he's got deep ties to boston. and my take was there's no doubt that the boston marathon is a worldwide known event, but unlike many of the targets, a lot of people really have used in the past, there's something specific to boston about it. there's something specific about the finish line and